dnl Turn on the additional warnings last, so -Werror doesn't affect other tests.

AC_DEFUN([LM_COMPILE_WARNINGS],[
   if test -f $srcdir/autogen.sh; then
	default_compile_warnings="error"
    else
	default_compile_warnings="no"
    fi

    AC_ARG_WITH(compile-warnings, [  --with-compile-warnings=[no/yes/error] Compiler warnings ], [enable_compile_warnings="$withval"], [enable_compile_warnings="$default_compile_warnings"])

    warnCFLAGS=
    if test "x$GCC" != xyes; then
	enable_compile_warnings=no
    fi

    warning_flags=
    realsave_CFLAGS="$CFLAGS"

    case "$enable_compile_warnings" in
    no)
	warning_flags=
	;;
    yes)
	warning_flags="-Wall -Wunused -Wmissing-prototypes -Wmissing-declarations"
	;;
    maximum|error)
	warning_flags="-Wall -Wunused -Wchar-subscripts -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wpointer-arith"
	CFLAGS="$warning_flags $CFLAGS"
	for option in -Wsign-promo -Wno-sign-compare; do
		SAVE_CFLAGS="$CFLAGS"
		CFLAGS="$CFLAGS $option"
		AC_MSG_CHECKING([whether gcc understands $option])
		AC_TRY_COMPILE([], [],
			has_option=yes,
			has_option=no,)
		CFLAGS="$SAVE_CFLAGS"
		AC_MSG_RESULT($has_option)
		if test $has_option = yes; then
		  warning_flags="$warning_flags $option"
		fi
		unset has_option
		unset SAVE_CFLAGS
	done
	unset option
	if test "$enable_compile_warnings" = "error" ; then
	    warning_flags="$warning_flags -Werror"
	fi
	;;
    *)
	AC_MSG_ERROR(Unknown argument '$enable_compile_warnings' to --enable-compile-warnings)
	;;
    esac
    CFLAGS="$realsave_CFLAGS"
    AC_MSG_CHECKING(what warning flags to pass to the C compiler)
    AC_MSG_RESULT($warning_flags)

    WARN_CFLAGS="$warning_flags"
    AC_SUBST(WARN_CFLAGS)
])